假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。文中共有10处语言错误，每句中最多有两处。每处错误仅涉及一个单词的增加、删除或修改。 增加：在缺词处加一个漏字符号（∧），并在其下面写出该加的词。
删除：把多余的词用斜线〔\〕划掉。
修改：在错的词下划一横线，并在该词下面写出修改后的词。
注意：1.每处错误及其修改均仅限一词；
只允许修改10处，多者（从第11处起）不计分。
Walter ’s goal in life was become a successfully doctor.He knew he had to finish high school first,so he put his heart into his study-- in particular,biology,chemistry,and maths.Because he worked hard at these subjects,Walter became good at it.However, Walter forgot that he needed to master some other subjects beside those he had been chosen.As a result,Walter fails both English and Chinese in the end of the second school year.But he had to repeat these subjects and he was almost unable to graduate like planned.Walter learned a good lesson.